HIGH FIVE: The Mets appear willing to add a fifth year to a contract offer in order to woo Jason Bay to Flushing. Photo: Matthew West

“Bay Watch” could soon have the desired ending for the Mets.

The Amazin’s emerged as the leading contender yesterday for Jason Bay’s services as GM Omar Minaya got off the mat after a rough week and redoubled his efforts to land the All-Star left fielder.

A team source confirmed a report the Mets are considering adding a fifth year to their original four-year, roughly $65 million offer to the 31-year-old veteran.

Minaya was in serious negotiations with Bay’s agent, Joe Urbon, over the past two days, but the Mets indicated they only would increase their overall offer to $75 million if they decide to add a fifth year to their heavily back-loaded proposal.

The Mets also might just increase the four-year offer to $75 million instead of committing to a fifth year, a source said.

The Mets downplayed their reported interest in joining the sweepstakes for fellow big-ticket left fielder Matt Holliday, saying instead the club will continue to monitor his talks with the Cardinals and others rather than jump in with an offer.

The Mets still believe Bay is a better fit than the younger Holliday, 29, in part because their research has told them the dead-pull hitting Bay meshes better with Citi Field than Holliday, whose power is to gaps, which are vast in Flushing.

But Minaya’s willingness to look at Holliday and consider a fifth year for Bay were seen as signs that the Mets want resolution soon nearly a week after they tendered their first offer to Bay at the end of the Winter Meetings.

A team source, meanwhile, confirmed talks with free-agent catcher Bengie Molina had slowed considerably because the 35-year-old Molina wants a guaranteed third year, which the Mets are reluctant to give him.

As for Bay, the Mets are being careful about adding a fifth year because of concerns about the injury-prone Bay’s ability to complete such a lengthy deal, not to mention worries that the competition for him isn’t as strong as Urbon is making it out to be.

There have been national media reports of a “mystery team” that already has tendered Bay a five-year offer, but the possible identities of that team seemingly continue to diminish.

Bay’s previous team, the Red Sox, made it clear yesterday during the news conference to announce outfielder Mike Cameron’s signing that Bay won’t be back in Boston in 2011.

Red Sox GM Theo Epstein spoke about Bay in the past tense when asked by Boston reporters if Cameron’s signing closed the door on a potential return by Bay.

“Whichever team does sign [Bay] is going to get a quality person and a quality player,” Epstein said.

Meanwhile, three other teams thought to be pursuing Bay — the Mariners, Angels and Giants — all reportedly signaled interest in him was minimal.

Minaya’s renewed activity on the free-agent front yesterday appeared to indicate the beleaguered Mets executive is trying to bounce back after being caught flat-footed this week when the Red Sox signed his No. 1 free-agent pitching target in John Lackey and the rival Phillies landed Cy Young winner Roy Halladay.

* Jose Reyes was among the athletes who underwent an experimental plasma recycling process performed by a Canadian physician who has now been charged in Canada with selling an unapproved drug known as Actovegin.

Reyes had the procedure last summer in hopes of speeding his recovery from hamstring and calf injuries.

The doctor, Anthony Galea, is charged with importing a drug made from calves’ blood, according to published reports.

* While the Mets await word from former Angels pitcher Kelvim Escobar on their offer of a minor-league contract, the veteran right-hander continues to receive strong interest from several other clubs.

A Mets source indicated last night that the team isn’t confident of landing Escobar.